Cutting fluid



ilnited States Patent @hhce 3,h?l,5d Patented Jan. 1, 1963 3,tl7l,545 CUTTEN S FLUH) Robert H. Davis, Massapequa, N.Y., and Ernst Lang,

Union City, N..l., assignors to Socony Mobil Bil Company, Inc, a corporation of New York No Drawing. Filed Feb. 8, 1966, Ser. No. 7,117

3 Qtaims. (til. 252--34.7)

This invention concerns an aqueous composition adapted, particularly in diluted form, for use as a coolant and lubricating agent in metal cutting, metal grinding and similar operations.

In the machining of metals in operations such as cutting, threading, tapping and the like, it is customary to flood the tool and work with a coolant to carry away heat from the tool and Work, and normally such coolants are also so compounded as to provide lubrication. Due to the high unit pressures involved, particularly in highspeed operations, the fluid, if used also as a lubricant, must be an exceptionally capable coolant. Many such fluids are emulsified petroleum oil base fluids, although in some cases it would appear that non-petroleum base fluids are more acceptable.

In Patent No. 2,625,509 issued January 13, 1953, is disclosed a non-petroleum base lubricant which represented a considerable improvement over prior composi tions. This lubricant appeared sta le, non-corrosive and rust-inhibiting, but was found in service to have certain undesirable features. The foam formation was considered excessive, the composition was found to form insoluble soaps, and operators complained of irritation of the nose and throat when using the lubricant.

In application Serial Number 726,335, filed April 4, 1958, now U.S. Patent No. 2,999,814, is disclosed an improved non-petroleum base lubricant which represented a considerable improvement over prior compositions, includin the compositions of Patent No. 2,625,509. The excessive foam formation was eliminated as Well as the formation of insoluble soaps. The operators noted no irritation of the nose and throat when using this lubri cant. However, the lubricant, when stored for long periods prior to use, was found to be subject to spoilage. Since these lubricants may be kept at ambient or higher temperature for substantial periods in some instances, an improved product having all the fine qualities of the prior lubricants of Patent No. 2,625,509 and application Serial Number 726,335, but with increased resistance to spoilage from bacterial decomposition, was desired.

It is an object of this invention to provide an aqueous composition of the class described, which is effective as a coolant and lubricant and which is free from the undesirable features recited above.

Another object of this invention is to provide a more stable, non-corrosive, rust-inhibiting coolant-lubricant.

Another object of this invention is the provision of a highly stable coolant-lubricant forming a soft, residual film on metal surfaces, which film is easily removed therefrom by water-washing.

Still another object is the provision of a lubricant having resistance to bacterial decomposition under extended storage periods and adverse conditions which still provides adequate lubrication and cooling in metalworking operations and can be used with hard water with a minimum formation of insoluble soaps.

Still other objects will be apparent from the following detailed description of the invention.

Compounders of lubricant formulations can appreciate the problem of compounding stable water base lubricants having high lubrication and cooling eihciency in metalworking operations. While any single property can readily be provided from known art, any attempt to improve a single quality adversely affects other properties and hence it is generally necessary to sacrifice certain stability for lubricating efiiciency, or foaming properties for lubricating and cooling effici ncy, etc.

We have found that a balanced formulation having unusual lubrication and cooling efiiciency, free from excessive foam formation and nasal irritation to the user and yet possessing unusual storage stability, can be obtained by careful combination of a reaction product of alkanolamines with organic aliphatic acids, mixed soaps of alicanolamine fatty acids, potassium soaps of fatty acids, an alkanolamine phosphate, a rust inhibitor and a germicide.

By substituting the potassium soap and thealkanolamine organic acid reaction product for the sugar-derived material and reducing the nitrite content in the formulation, resistance to spoilage was increased, without damage to lubricating efficiency and cooling-efficiency. A combination of three germicides has been found which provides exceptional stability of the product and is not detrimental to the formulation as a cutting and metalworking formulation. High anti-wear properties are designed into the formulation by the presence of the potassium soap of castor oil fatty acids in critical amount. Corrosion inhibition is provided by the combination of amine soaps, amine phosphates and small quantities of sodium nitrite. The amine phosphate in critical proportion provides fine anti-weld properties to the formulation.

The alkanolarnine reaction product consists of substantially completely neutral di-ethanolamine salts of one part by weight para-tertiary butyl benzoic acid and two parts by weight of a mixture of aliphatic carboxylic acids derived from an oxidized petroleum fraction and having carbon chain lengths between C and C and a mean carbon chain length of C Castor oil fatty acids are generally characterized by the following specifications:

Acid number -185 Saponification number -195 Iodine number 85-95 The alkanolamine phosphate is preferably tri-ethanolamine phosphate, although monoor di-ethanolamine phosphate may be substituted in whole or in part. The phosphate may be formed by adding to the formulation the desired amount of tri-ethanolamine and phosphoric acid. Preferably, however, the castor oil fatty acids are reacted with potassium hydroxide to obtain the desired amount of potassium soaps of fatty acids. Tri-ethanolamine is then added to react with the remaining castor oil fatty acids to produce mixed soaps of tri-ethanolamine fatty acids. Water and phosphoric acid is then added to react with the excess tri-ethanolamine, producing the triethanolamine phosphate. The alkanolamine-organic acid reaction product is then added followed by a. combination of three germicides. The combination germicide found satisfactory is phenol, the sodium salt of ortho phenyl phenol and the methyl ester of p-hydroxy benzoic acid. A rust inhibitor such as sodium nitrite is then added.

Balanced proportions of the several components discussed above must be used to provide a composition having all the desired properties. For instance, too little of the alkanolamine-organic acid reaction product will lower corrosion resistance; too much of this component upsets relationships with other components. Too much soap causes excess foaming. The stability of the composition in hard water depends upon the proper proportion of the castor oil fatty acid soaps present. An excess of phosphate together with an excess of rust inhibitor, such as sodium nitrite, results in instability of the composition with separation of some of the components. In addition, if less than the specified quantity of germicide is used, the composition will not have the required germicidal properties and may develop objectionable odors during storage and service. If too great a quantity of rust inhibitor and germicide is used, some solid residue will form on the machine tool being used; this residue can cause sticking of moving machine parts. Such residues are removed with difliculty.

The compositions of this invention have the following balanced proportions, expressed in weight percent.

The compositions contemplated herein are compounded according to the following procedure, which is illustrated by a preferred composition (identified herein as Composition I). The castor oil fatty acids are charged to a steam-jacketed kettle, equipped with an agitator which is in operation throughout the preparation. The kettle is maintained at a temperature of about 120 F. and the potassium hydroxide is added. Then tri-ethanolamine and water are added in order with agitation being continued and temperature maintained at about 120 F. until a clear solution is obtained. The phosphoric acid is then introduced into the mixture. At constant temperature and continued agitation the reaction product of substantially completely neutral di-ethanolamine salts formed by reacting a sufficient amount of di-ethanolamine with one part by weight para-tertiary butyl benzoic acid and two parts by weight of a mixture of aliphatic carboxylic acids derived from an oxidized petroleum fraction and having carbon chain lengths between C and C and a mean carbon chain length of C is added. Phenol, the sodium salt of ortho phenyl phenol and the methyl ester of p-hydroxy benzoic acid are then added in order. Finally the sodium nitrite is added and the formulation is complete.

Composition I, prepared by the foregoing procedure, has the following characteristics.

When the compositions of this invention are used as coolants and lubricants for metalworking, they are preferably used in diluted form. Recommended proportions are the following.

Operation:

Tapping l-1O to 120 Drilling l-lS to 130 Grinding 1-50 to 1-70 The compositions of this invention have been proven to be advantageous in a number of respects, as is demonstarted by the following test data.

Almen Pin Test Composition 1, diluted 1-10 with distilled water, withstood an OK load of 14,000 pounds per square inch.

Dilution A 4 This test is described in Proc. A.P.I., 1932, pages 118- 130.

Tapping Efficiency In the measurement of tapping efficiency of an oil, a series of holes is accurately drilled in a test metal, namely, SAE 1020 hot rolled steel. These holes are subsequently tapped with a. series of taps in a drill press equipped with a table, which is free to rotate about the center, being mounted on ball bearings. A torque arm is attached to this floating table and this arm, in turn, actuates a spring scale so that the actual torque during tapping with the oil being evaluated is measured directly. The same taps used in evaluating the test oil are employed in tapping with a standard reference oil, which has arbitrarily been assigned an efficiency of percent. The average torque for the test oil is compared to that of the standard and a relative efliciency is calculated on a percentage basis. For example,

Torque with standard reference oil 19.3 Torque with test oil 19.8 Relative efficiency of test oil Standard, Socony Mobil Solvac 410 diluted l15 with tap water=l00%. Composition I diluted 1-15 with distilled water =98.

Corrosion Test Composition I is shown to be non-corrosive to ferrous products, by a humidity cabinet test on turnings of malleable iron treated with various dilutions thereof.

l l Drum. aterman? a 1-15 distilled water No corrosion. 1-30 distilled water No corrosion. 1-45 distilled water Corrosion.

Composition I was subjected to the following foam the bottom of the cylinder. The return line is about 8' inches above the level of the liquid. Circulation is started and readings are taken at 5, l0 and 15 minutes to note foam formation. Circulation is stopped and readings taken at 5, l0 and 15 minutes to record settling of the foam. An excellent product will give from 500 to 1000 mls. of foam, which will completely settle in 5 minutes. Composition I exhibited 900 mls. of foam, which settled in approximately 5 minutes. The product was, therefore, considered satisfactory by the foam test.

Composition I was also found to be free from irritation to the nose and throat of members of a test panel. When Composition I was diluted with distilled water (l-SO) and atomized before the panel, no irritation was experienced.

In a gum test it was found that Composition I formed a soft residual film on a metal surface, which film is removed readily with water. This test consists of evaporating 15 mls. of a 1-5 dilution on a 6-inch watch crystal in a forced draft oven at F. for 48 hours.

Composition I was tested in the field using all types of machining operations, and the machining efiiciency was found to be as good or better than that of the formulation disclosed in application Serial Number 726,335. These tests showed that Composition I was superior to the formulations of Serial Number 726,335 with respectto resistance to spoilage. The all-around performance of Composition I has been superior to other products of this type in operations ranging from tapping to grinding.

We claim: 1. An aqueous coolant and lubricant formed by mixing in order the following components:

Weight percent Castor oil fatty acids 2.50-7.50 Potassium hydroxide 0.23-0.70 Alkanolamine selected from the group consisting of mono-, diand tri-ethanolamine 8.5-1 1.5 Water 83.18-70.05 Phosphoric acid 1.69-2.25 A reaction product consisting of substantially completely neutral di-ethanolamine salts of one part by weight para-tertiary butyl benzoic acid and two parts by weight of a mixture of aliphatic carboxylic acids derived from any oxidized petroleum fraction and having carbon chain lengths between G, and C and a mean carbon chain length of C 1.50-3.00 Phenol 0.10-1.00 Ortho phenyl phenol-sodium salt 0.50-1.00 Methyl ester of p-hydroxy benzoic acid 1.50-2.00 Sodium nitrite 0.30-l.00

2. An aqueous coolant and lubricant formed by mixing in order the following components:

Weight percent A reaction product consisting of substantially completely neutral di-ethanolamine salts of one part by weight para-tertiary butyl benzoic acid and two parts by weight of a Weight percent mixture of aliphatic carboxylic acids derived from any oxidized petroleum fraction and having carbon chain lengths between 3. An aqueous coolant and lubricant formed by mixing in order the following components:

Weight percent Castor oil fatty acids 5.00 Potassium hydroxide 0.47 Tri-ethanolamine 11.50 Water 74.38 Phosphoric acid 2.25 A reaction product consisting of substantially com pletely neutral di-ethanolamine salts of one part by weight para-tertiary butyl benzoic acid and two parts by weight of a mixture of aliphatic carboxylic acids derived from any oxidized petroleum fraction and having carbon chain lengths between G; and C and a mean carbon chain length of C 2.00 Phenol 0.90 Ortho phenyl phenol-sodium salt 1.00 Methyl ester of p-hydroxy benzoic acid 2.00 Sodium nitrite 0.50

References Cited in the file of this patent UNITED STATES PATENTS 1,879,351 Lehmann et al Sept. 27, 1932 2,481,585 Freeman Sept. 13, 1949 2,625,509 Lang Jan. 13, 1953 2,825,693 Beaubien et a1 Mar. 4, 1958 2,999,814 Laug Sept. 12, 196] 

1. AN AQUEOUS COOLANT AND LUBRICANT FORMED BY MIXING IN ORDER THE FOLLOWING COMPONENTS: WEIGHTS PERCENT CASTOR OIL FATTY ACIDS 2.50-7.50 POTASSIUM HYDROXIDE 0.23-0.70 ALKANOLAMINE SELECTED FROM THE GROUP CONSISTING OF MONO-, DI- AND TRI-ETHANOLAMINE 8.5-11.5 WATER 83.18-70.05 PHOSPHORIC ACID 1.69-2.25 A REACTION PRODUCT CONSISTING OF SUBSTANTIALLY COMPLETELY NEUTRAL DI-ETHANOLAMINE SALTS OF ONE PART BY WEIGHT PARA-TERTIARY BUTYL BENZOIC ACID AND TWO PARTS BY WEIGHT OF A MIXTURE OF ALIPHATIC CARBOXYLIC ACIDS DERIVED FROM ANY OXIDIZED PETROLEUM FRACTION AND HAVING CARBON CHAIN LENGTHS BETWEEN C7 AND C14 AND A MEAN CARBON CHAIN LENGTH OF C8 1.50-3.0 PHENOL 0.10-1.00 ORTHOPHENYL PHENOL-SODIUM SALT 0.50-1.00 METHYL ESTER OF P-HYDROXY BENZOIC ACID 1.50-2.00 SODIUM NITRATE 0.30-1.00 